1. Field of the Invention
This invention relates to a spectral imaging system for light aircraft remote sensing and in particular to a high-definition hyperspectral imaging system (HDHIS) that integrates a grating based imaging spectrometer and a CCD digital camera for concurrent pushbroom hyperspectral imaging and high resolution photographic imaging.
2. Description of Related Art
There are increasing concerns about the environmental change of our earth and the effective management of human activities altering and using our planet. Modern terrestrial remote sensing, featuring digital spectral image data collection technologies, has been increasingly used for quickly and efficiently mapping, imaging and monitoring our planet earth from global scale to regional. The first commercial 1-meter resolution satellite, US Space Imaging's Ikonos, was successfully launched in August 1999, joining the Landset, Spot, and other operational Earth observation satellites and providing 1-meter-resolution photographs of almost any place on earth. Aerial remote sensing platforms are indispensable and valuable adjuncts to the latest Earth observation satellites. New generations of smaller, lighter, power saving, cheaper and better hyperspectral/multispectral imaging systems are becoming operational to fly with diverse low-cost flying platforms in traditional light aircraft, balloons and airships to the latest unmanned aerial vehicles (UAVs). Quickly available higher spatial and spectral resolution airborne spectral images with extended dynamic range are broadly desired for regional, special and satellite-demanded ground truth remote sensing applications.
In U.S. Pat. No. 5,790,188 issued to Xiuhong Sun on Aug. 4, 1998 and assigned to Flight Landata, Inc. of Lawrence, Mass., a variable interference filter imaging spectrometer (VIFIS) system is described which acquires ground track spectral images from air or space with a two-dimensional field of view and generates spectral imagery from three channels of synchronized video outputs. The synchronized video stream outputting from each camera is fed to a control and interface unit where a composite analog signal is formed from the individual output video signals for recording on an analog video recorder. A digital signal is also generated for recording on a computer disk. Control of the shutter speed of each of 3 cameras is provided.
In U.S. Pat. No. 6,211,906 issued to Xiuhong Sun on Apr. 3, 2001 and assigned to Flight Landata, Inc. of Lawrence, Mass., a computerized component, variable interference imaging spectrometer (C2VIFIS) is described for airborne remote sensing and data acquisition with a two dimensional field of view. Spectrally filtered video data is obtained from three synchronized CCD-imager modules or cameras wherein one imager module has a visible range variable interference filter on its surface, a second imager module has a near-infrared variable interference filter on its surface, and a third imager module has a bandpass filter attached to the imager. An alternating staring/scanning method is used to optimize a pushbroom hyperspectral image data set with a photogrammetric reference.
A computerized airborne multicamera imaging system (CAMIS) is described in a paper by Xiuhong Sun, James Baker and Richard Hordon entitled “Computerized Airborne Multicamera Imaging System” (CAMIS), Second International Airborne Remote Sensing Conference and Exhibition, San Francisco, Calif., 22–27 Jun. 1996. The CAMIS comprises a personal computer such as a Pentium 133 MHz computer which receives data from three synchronized CCD cameras with interchangeable narrow-band interference filters and a variable interference filter. Simultaneous, digital multichannel images are directly recorded onto SCSI drives without compression.
An improved computerized airborne multicamera imaging system (CAMIS) with four camera integration for remote sensing is described in a paper by Xiuhong Sun, James Baker and Richard Hordon entitled “Computerized Airborne Multicamera Imaging System (CAMIS) and Its Four-Camera Application”, Third International Airborne Remote Sensing Conference and Exhibition, 7–10 Jul. 1997, Copenhagen, Denmark. This improved CAMIS is a direct-sensor-to-computer imaging system which has integrated real-time positioning, a live moving map, and a live composite image display window for four cameras into a compact personal computer running under Windows NT. This paper also shows that a sequence of four channel CAMIS snapshots can be composed and mosaiked as a natural/NIR color composite pair with larger coverage, in which spectral characteristics beyond human eyes become easily recognized because of the large scale aerial multispectral viewing.